type student struct{
	name string
	number int
	zhuanye string
	yuwen float32
	shuxue float32
	yingyu float32
	lishi float32
	chengxu float32
	tiyu float32
	next *student
} 
func creat()*student                                               //1,创建链表，并输入学生信息

func luruyuwen(head *student)*student                              //2-1-录入语文成绩

func lurushuxue(head *student)*student		                       //2-2-录入数学成绩

func luruyingyu(head *student)*student		                        //2-3-录入英语成绩

func lurulishi(head *student)*student	                        	//2-4-录入历史成绩

func luruchengxu(head *student)*student	                            //2-5-录入程序成绩
                        
func lurutiyu(head *student)*student	                            //2-6-录入体育成绩

func luru(head *student)*student	                              	//2-录入学生各科成绩

func zengjia(head *student)			                                //3-增加学生信息  

func shanchu(head *student)*student	                                //4-删除学生信息
        
func xiugai(head *student)*student		                            //5-通过姓名和学号去修改学生数据

func cxyuwen(head *student)()		                                //6-1-查询语文成绩排名

func cxshuxue(head *student)()		                                //6-2-查询数学成绩排名

func cxyingyu(head *student)()		                                //6-3-查询英语成绩排名

func cxlishi(head *student)()		                                //6-4-查询历史成绩排名

func cxchengxu(head *student)()		                                //6-5-查询程序成绩排名

func cxtiyu(head *student)()			                            //6-6-查询体育成绩排名

func cxpaiming(head *student)()	                                    //6-查询某一科的成绩排名 

func chaxunchengji(head *student)()	                                //7-查询学生成绩

func bujige(head *student)()		                               	//8-统计所有不及格科目超过两科的学生名单

func put(head *student)			                                    //9-输出学生信息